New Compounds II

ABSTRACT

The present invention relates to compounds of formula (I), 
     
       
         
         
             
             
         
       
     
     and their pharmaceutically acceptable salts, solvates, hydrates, geometrical isomers, tautomers, optical isomers or N-oxides, which are inhibitors of SSAO activity. The invention further relates to pharmaceutical compositions comprising these compounds and to the use of these compounds for the treatment of medical conditions wherein inhibition of SSAO activity is beneficial, such as such as inflammatory diseases and immune disorders.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No.13/062,366, filed Mar. 4, 2011, now allowed, which is a National Stageapplication of co-pending PCT application PCT/EP2009/062018 filed Sep.16, 2009, which application claims priority from SE Application No.0801980-4 filed Sep. 16, 2008, and U.S. Ser. No. 61/106,727 filed Oct.20, 2008. The above mentioned applications are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

The present invention relates to new pyrazolo[4,3-c]pyridine compoundsof formula (I), which are inhibitors of SSAO activity. The inventionalso relates to pharmaceutical compositions comprising these compoundsand to the use of these compounds in the treatment or prevention ofmedical conditions wherein inhibition of SSAO activity is beneficial,such as such as inflammatory diseases and immune disorders.

BACKGROUND ART

Semicarbazide-sensitive amine oxidase (SSAO), otherwise known asVascular Adhesion Protein-1 (VAP-1) or Amine Oxidase, Copper Containing3 (AOC3), belongs to the copper-containing amine oxidase family ofenzymes (EC.1.4.3.6). Members of this enzyme family are sensitive toinhibition by semicarbazide and utilize cupric ion and protein-derivedtopa quinone (TPQ) cofactor in the oxidative deamination of primaryamines to aldehydes, hydrogen peroxide, and ammonia according to thefollowing reaction:

RCH₂NH₂+O₂→R—CHO+H₂O₂+NH₃

Known substrates for human SSAO include endogenous methylamine andaminoacetone as well as some xenobiotic amines such as benzylamine[Lyles, Int. J. Biochem. Cell Biol. 1996, 28, 259-274; Klinman, Biochim.Biophys. Acta 2003, 1647(1-2), 131-137; Mátyus et al., Curr. Med. Chem.2004, 11(10), 1285-1298; O'Sullivan et al., Neurotoxicology 2004,25(1-2), 303-315]. In analogy with other copper-containing amineoxidases, DNA-sequence analysis and structure determination suggest thatthe tissue-bound human SSAO is a homodimeric glycoprotein consisting oftwo 90-100 kDa subunits anchored to the plasma membrane by a singleN-terminal membrane spanning domain [Morris et al., J. Biol. Chem. 1997,272, 9388-9392; Smith et al., J. Exp. Med. 1998, 188, 17-27; Airenne etal., Protein Science 2005, 14, 1964-1974; Jakobsson et al., ActaCrystallogr. D Biol. Crystallogr. 2005, 61(Pt 11), 1550-1562].

SSAO activity has been found in a variety of tissues including vascularand non-vascular smooth muscle tissue, endothelium, and adipose tissue[Lewinsohn, Braz. J. Med. Biol. Res. 1984, 17, 223-256; Nakos & Gossrau,Folia Histochem. Cytobiol. 1994, 32, 3-10; Yu et al., Biochem.Pharmacol. 1994, 47, 1055-1059; Castillo et al., Neurochem. Int. 1998,33, 415-423; Lyles & Pino, J. Neural. Transm. Suppl. 1998, 52, 239-250;Jaakkola et al., Am. J. Pathol. 1999, 155, 1953-1965; Morin et al., J.Pharmacol. Exp. Ther. 2001, 297, 563-572; Salmi & Jalkanen, TrendsImmunol. 2001, 22, 211-216]. In addition, SSAO protein is found in bloodplasma and this soluble form appears to have similar properties as thetissue-bound form [Yu et al., Biochem. Pharmacol. 1994, 47, 1055-1059;Kurkijarvi et al., J. Immunol. 1998, 161, 1549-1557]. It has recentlybeen shown that circulating human and rodent SSAO originates from thetissue-bound form [Göktürk et al., Am. J. Pathol. 2003, 163(5),1921-1928; Abella et al., Diabetologia 2004, 47(3), 429-438; Stolen etal., Circ. Res. 2004, 95(1), 50-57], whereas in other mammals theplasma/serum SSAO is also encoded by a separate gene called AOC4[Schwelberger, J. Neural. Transm. 2007, 114(6), 757-762].

The precise physiological role of this abundant enzyme has yet to befully determined, but it appears that SSAO and its reaction products mayhave several functions in cell signalling and regulation. For example,recent findings suggest that SSAO plays a role in both GLUT4-mediatedglucose uptake [Enrique-Tarancon et al., J. Biol. Chem. 1998, 273,8025-8032; Morin et al., J. Pharmacol. Exp. Ther. 2001, 297, 563-572]and adipocyte differentiation [Fontana et al., Biochem. J. 2001, 356,769-777; Mercier et al., Biochem. J. 2001, 358, 335-342]. In addition,SSAO has been shown to be involved in inflammatory processes where itacts as an adhesion protein for leukocytes [Salmi & Jalkanen, TrendsImmunol. 2001, 22, 211-216; Salmi & Jalkanen, in “Adhesion Molecules:Functions and Inhibition” K. Ley (Ed.), 2007, pp. 237-251], and mightalso play a role in connective tissue matrix development and maintenance[Langford et al., Cardiovasc. Toxicol. 2002, 2(2), 141-150; Göktürk etal., Am. J. Pathol. 2003, 163(5), 1921-1928]. Moreover, a link betweenSSAO and angiogenesis has recently been discovered [Noda et al., FASEBJ. 2008, 22(8), 2928-2935].

Several studies in humans have demonstrated that SSAO activity in bloodplasma is elevated in conditions such as congestive heart failure,diabetes mellitus, Alzheimer's disease, and inflammation [Lewinsohn,Braz. J. Med. Biol. Res. 1984, 17, 223-256; Boomsma et al., Cardiovasc.Res. 1997, 33, 387-391; Ekblom, Pharmacol. Res. 1998, 37, 87-92;Kurkijärvi et al., J. Immunol. 1998, 161, 1549-1557; Boomsma et al.,Diabetologia 1999, 42, 233-237; Meszaros et al., Eur. J. Drug Metab.Pharmacokinet. 1999, 24, 299-302; Yu et al., Biochim. Biophys. Acta2003, 1647(1-2), 193-199; Matyus et al., Curr. Med. Chem. 2004, 11(10),1285-1298; O'Sullivan et al., Neurotoxicology 2004, 25(1-2), 303-315;del Mar Hernandez et al., Neurosci. Lett. 2005, 384(1-2), 183-187]. Themechanisms underlying these alterations of enzyme activity are notclear. It has been suggested that reactive aldehydes and hydrogenperoxide produced by endogenous amine oxidases contribute to theprogression of cardiovascular diseases, diabetic complications andAlzheimer's disease [Callingham et al., Prog. Brain Res. 1995, 106,305-321; Ekblom, Pharmacol. Res. 1998, 37, 87-92; Yu et al., Biochim.Biophys. Acta 2003, 1647(1-2), 193-199; Jiang et al., Neuropathol ApplNeurobiol. 2008, 34(2), 194-204]. Furthermore, the enzymatic activity ofSSAO is involved in the leukocyte extravasation process at sites ofinflammation where SSAO has been shown to be strongly expressed on thevascular endothelium [Salmi et al., Immunity 2001, 14(3), 265-276; Salmi& Jalkanen, in “Adhesion Molecules: Functions and Inhibition” K. Ley(Ed.), 2007, pp. 237-251]. Accordingly, inhibition of SSAO has beensuggested to have a therapeutic value in the prevention of diabeticcomplications and in inflammatory diseases [Ekblom, Pharmacol. Res.1998, 37, 87-92; Salmi et al., Immunity 2001, 14(3), 265-276; Salter-Cidet al., J. Pharmacol. Exp. Ther. 2005, 315(2), 553-562].

SSAO knockout animals are phenotypically overtly normal but exhibit amarked decrease in the inflammatory responses evoked in response tovarious inflammatory stimuli [Stolen et al., Immunity 2005, 22(1),105-115]. In addition, antagonism of its function in wild type animalsin multiple animal models of human disease (e.g. carrageenan-induced pawinflammation, oxazolone-induced colitis, lipopolysaccharide-induced lunginflammation, collagen-induced arthritis, endotoxin-induced uveitis) bythe use of antibodies and/or small molecules has been shown to beprotective in decreasing the leukocyte infiltration, reducing theseverity of the disease phenotype and reducing levels of inflammatorycytokines and chemokines [Kirton et al., Eur. J. Immunol. 2005, 35(11),3119-3130; Salter-Cid et al., J. Pharmacol. Exp. Ther. 2005, 315(2),553-562; McDonald et al., Annual Reports in Medicinal Chemistry 2007,42, 229-243; Salmi & Jalkanen, in “Adhesion Molecules: Functions andInhibition” K. Ley (Ed.), 2007, pp. 237-251; Noda et al., FASEB J. 200822(4), 1094-1103; Noda et al., FASEB J. 2008, 22(8), 2928-2935]. Thisanti-inflammatory protection seems to be afforded across a wide range ofinflammatory models all with independent causative mechanisms, ratherthan being restricted to one particular disease or disease model. Thiswould suggest that SSAO may be a key nodal point for the regulation ofthe inflammatory response, and it therefore seems likely that SSAOinhibitors may be effective anti-inflammatory drugs in a wide range ofhuman diseases.

The invention described here relates to novel pyrazolo[4,3-c]pyridinederivatives as a new class of chemically distinct SSAO inhibitors withbiological, pharmacological, and pharmacokinetic characteristics thatmake them suitable for use as prophylactic or therapeutic agents in awide range of human inflammatory diseases and immune disorders. Thistherapeutic capacity is designed to block SSAO enzyme action, reducingthe levels of pro-inflammatory enzyme products (aldehydes, hydrogenperoxide and ammonia) whilst also decreasing the adhesive capacity ofimmune cells and correspondingly their activation and finalextra-vasation. Diseases where such an activity is expected to betherapeutically beneficial include all diseases where immune cells playa prominent role in the initiation, maintenance or resolution of thepathology, such as multiple sclerosis, arthritis and vasculitis.

Pyrazolo[4,3-c]pyridine compounds have been disclosed in WO 94/03453 asangiotensin II receptor antagonists for use in the treatment ofhypertension and congestive heart failure. EP 594001 describes4-phenylpyrazolo[4,3-c]pyridine compounds as serotonin reuptakeinhibitors for use in the treatment of depression and obsessivecompetitive disorder. SSAO inhibitors have been described in WO02/38153, which discloses certain tetrahydroimidazo[4,5-c]pyridinederivatives that are useful in the treatment of diabetes and vascularcomplications.

DISCLOSURE OF THE INVENTION

It has surprisingly been found that the new pyrazolo[4,3-c]pyridinecompounds of formula (I) are inhibitors of SSAO activity. They aretherefore useful in the treatment or prevention of diseases in whichinhibition of SSAO activity is beneficial. As such they are potentiallyuseful for the treatment or prevention of inflammation, inflammatorydiseases, immune or autoimmune disorders. Consequently, the inventionrelates to a compound of formula (I),

or a pharmaceutically acceptable salt, solvate, hydrate, geometricalisomer, tautomer, optical isomer or N-oxide thereof, wherein:R¹ is one, two or three substituents independently selected fromhalogen, cyano, C₁₋₆-alkyl, halo-C₁₋₆-alkyl and C₁₋₆-alkoxy;R² is a 4- to 7-membered heterocyclic ring containing 1 or 2 heteroatomsindependently selected from O, S and N(R³), and wherein ring carbonatoms are optionally substituted with R⁴;R³ is selected from hydrogen, C₁₋₆-alkyl, hydroxy-C₁₋₆-alkyl,cyano-C₁₋₆-alkyl, halo-C₁₋₆-alkyl, C₁₋₆-alkoxy-C₁₋₆-alkyl, C₁₋₆-acyl andC₁₋₆-alkylsulfonyl;R⁴ is independently selected from halogen, hydroxy, C₁₋₆-alkyl,hydroxy-C₁₋₆-alkyl, C₁₋₆-alkoxy-C₁₋₆-alkyl, cyano-C₁₋₆-alkyl,halo-C₁₋₆-alkyl and C₁₋₆-alkoxy; and a is 0, 1 or 2;provided that the compound is not:

-   3-(3,4-dichlorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine,    or-   1-(1-methylpiperidin-4-yl)-3-[4-(trifluoromethyl)phenyl]-1H-pyrazolo[4,3-c]pyridine.

More preferred compounds of formula (I) are those wherein:

R¹ is selected from halogen, cyano and C₁₋₄-alkyl; andR² is a 5- to 6-membered heterocyclic ring containing 1 or 2 heteroatomsindependently selected from O, S and N(R³), and wherein ring carbonatoms are optionally substituted with R⁴.

A preferred embodiment of the invention consists of compounds of formula(I′),

wherein R¹ is selected from halogen, cyano and C₁₋₄-alkyl;R² is a 5- to 6-membered heterocyclic ring containing 1 or 2 heteroatomsindependently selected from O, S and N(R³), and wherein ring carbonatoms are optionally substituted with R⁴;R³ is selected from hydrogen, C₁₋₄-alkyl, hydroxy-C₁₋₄-alkyl,cyano-C₁₋₄-alkyl, halo-C₁₋₄-alkyl, C₁₋₄-alkoxy-C₁₋₄-alkyl, C₁₋₄-acyl andC₁₋₄-alkylsulfonyl;R⁴, if present, is independently selected from C₁₋₄-alkyl,halo-C₁₋₄-alkyl, hydroxy-C₁₋₄-alkyl and C₁₋₄-alkoxy-C₁₄-alkyl; anda is 0 or 1.

A further preferred embodiment of the invention consists of compounds offormula (I″),

wherein R¹ is selected from halogen, cyano and C₁₋₄-alkyl;R² is a saturated 5- to 6-membered heterocyclic ring containing 1heteroatom selected from O and N(R³), and wherein ring carbon atoms areoptionally substituted with R⁴;R³ is hydrogen, C₁₋₄-alkyl or cyano-C₁₋₄-alkyl;R⁴, if present, is independently methyl or ethyl.

Even more preferred compounds of formula (I″) are those wherein:

R¹ is fluoro, chloro or methyl;R² is a piperidine, tetrahydropyran or tetrahydrofuran ring;R³, if present, is hydrogen, methyl or cyanomethyl; andR⁴ is absent.

Specific preferred compounds of the invention are selected from thegroup consisting of:

-   3-(4-Fluorophenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-2-(tetrahydro-2H-pyran-4-yl)-2H-pyrazolo[4,3-c]pyridine;-   3-(4-Methylphenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-[(3R)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;-   {4-[3-(4-Chlorophenyl)-1H-pyrazolo[4,3-c]pyridin-1-yl]piperidin-1-yl}acetonitrile;-   3-(4-Chlorophenyl)-1-(tetrahydro-2H-pyran-4-ylmethyl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-[1-(methylsulfonyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]pyridine;-   1-(1-Acetylpiperidin-4-yl)-3-(4-chlorophenyl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-[1-(2-methoxyethyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-piperidin-3-yl-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-[(3S)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-(tetrahydrofuran-3-ylmethyl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-(1-ethylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Chlorophenyl)-1-(1-isopropylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Fluorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;-   3-(4-Fluorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine;-   4-[1-(Tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrile;    and-   4-[1-(1-Methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrile.

Another object of the present invention is a compound of formula (I) foruse in therapy. The compounds as defined above are useful as inhibitorsof SSAO activity. As such, they are useful in the treatment orprevention of conditions and diseases in which inhibition of SSAOactivity is beneficial. More specifically, they are useful for thetreatment or prevention of inflammation, inflammatory diseases, immuneor autoimmune disorders.

In particular, it is believed that compounds of formula (I) are usefulfor the treatment or prevention of arthritis (such as rheumatoidarthritis, juvenile rheumatoid arthritis, osteoarthritis and psoriaticarthritis), synovitis, vasculitis, conditions associated withinflammation of the bowel (such as Crohn's disease, ulcerative colitis,inflammatory bowel disease and irritable bowel syndrome),atherosclerosis, multiple sclerosis, Alzheimer's disease, vasculardementia, pulmonary inflammatory diseases (such as asthma, chronicobstructive pulmonary disease and acute respiratory distress syndrome),fibrotic diseases (including idiopathic pulmonary fibrosis, cardiacfibrosis and systemic sclerosis (scleroderma)), inflammatory diseases ofthe skin (such as contact dermatitis, atopic dermatitis and psoriasis),systemic inflammatory response syndrome, sepsis, inflammatory and/orautoimmune conditions of the liver (such as autoimmune hepatitis,primary biliary cirrhosis, alcoholic liver disease, sclerosingcholangitis, and autoimmune cholangitis), diabetes (type I or II) and/orthe complications thereof, chronic heart failure, congestive heartfailure, ischemic diseases (such as stroke and ischemia-reperfusioninjury), and myocardial infarction and/or the complications thereof.

It is believed that the compounds of the invention are especially usefulfor the treatment or prevention of vasculitis, including, but notlimited to, giant cell arteritis, Takayasu's arteritis, Polyarteritisnodosa, Kawasaki disease, Wegener's granulomatosis, Churg-Strausssyndrome, microscopic polyangiitis, Henoch-Schnlein purpura,cryoglobulinemia, cutaneous leukocytoclastic angiitis and primaryangiitis of the central nervous system.

The invention thus includes the use of said compounds in the manufactureof a medicament for the treatment or prevention of the above-mentionedconditions and diseases. The invention also includes methods fortreatment or prevention of such conditions and diseases, comprisingadministering to a mammal, including man, in need of such treatment aneffective amount of a compound as defined above.

Methods delineated herein include those wherein the subject isidentified as in need of a particular stated treatment. Identifying asubject in need of such treatment can be in the judgment of a subject ora health care professional and can be subjective (e.g. opinion) orobjective (e.g. measurable by a test or diagnostic method).

In other aspects, the methods herein include those further comprisingmonitoring subject response to the treatment administrations. Suchmonitoring may include periodic sampling of subject tissue, fluids,specimens, cells, proteins, chemical markers, genetic materials, etc. asmarkers or indicators of the treatment regimen. In other methods, thesubject is prescreened or identified as in need of such treatment byassessment for a relevant marker or indicator of suitability for suchtreatment.

In one embodiment, the invention provides a method of monitoringtreatment progress. The method includes the step of determining a levelof diagnostic marker (Marker) (e.g., any target or cell type delineatedherein modulated by a compound herein) or diagnostic measurement (e.g.,screen, assay) in a subject suffering from or susceptible to a disorderor symptoms thereof delineated herein, in which the subject has beenadministered a therapeutic amount of a compound herein sufficient totreat the disease or symptoms thereof. The level of Marker determined inthe method can be compared to known levels of Marker in either healthynormal controls or in other afflicted patients to establish thesubject's disease status. In preferred embodiments, a second level ofMarker in the subject is determined at a time point later than thedetermination of the first level, and the two levels are compared tomonitor the course of disease or the efficacy of the therapy. In certainpreferred embodiments, a pre-treatment level of Marker in the subject isdetermined prior to beginning treatment according to this invention;this pre-treatment level of Marker can then be compared to the level ofMarker in the subject after the treatment commences, to determine theefficacy of the treatment.

In certain method embodiments, a level of Marker or Marker activity in asubject is determined at least once. Comparison of Marker levels, e.g.,to another measurement of Marker level obtained previously orsubsequently from the same patient, another patient, or a normalsubject, may be useful in determining whether therapy according to theinvention is having the desired effect, and thereby permittingadjustment of dosage levels as appropriate. Determination of Markerlevels may be performed using any suitable sampling/expression assaymethod known in the art or described herein. Preferably, a tissue orfluid sample is first removed from a subject. Examples of suitablesamples include blood, urine, tissue, mouth or cheek cells, and hairsamples containing roots. Other suitable samples would be known to theperson skilled in the art. Determination of protein levels and/or mRNAlevels (e.g., Marker levels) in the sample can be performed using anysuitable technique known in the art, including, but not limited to,enzyme immunoassay, ELISA, radiolabeling/assay techniques,blotting/chemiluminescence methods, real-time PCR, and the like.

DEFINITIONS

The following definitions shall apply throughout the specification andthe appended claims.

Unless otherwise stated or indicated, the term “C₁₋₆-alkyl” denotes astraight or branched alkyl group having from 1 to 6 carbon atoms. Forparts of the range “C₁₋₆-alkyl” all subgroups thereof are contemplatedsuch as C₁₋₅-alkyl, C₁₋₄-alkyl, C₁₋₃-alkyl, C₁₋₂-alkyl, C₂₋₆-alkyl,C₂₋₅-alkyl, C₂₋₄-alkyl, C₂₋₃-alkyl, C₃₋₆-alkyl, C₄₋₅-alkyl, etc.Examples of said “C₁₋₆-alkyl” include methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl and straight- andbranched-chain pentyl and hexyl.

Unless otherwise stated or indicated, the term “halo-C₁₋₆-alkyl” denotesa straight or branched C₁₋₆-alkyl group substituted by one or morehalogen atoms. Examples of said halo-C₁₋₆-alkyl include 2-fluoroethyl,fluoromethyl, trifluoromethyl and 2,2,2-trifluoroethyl.

Unless otherwise stated or indicated, the term “hydroxy-C₁₋₆-alkyl”denotes a straight or branched C₁₋₆-alkyl group that has a hydrogen atomthereof replaced with OH. Examples of said hydroxy-C₁₋₆-alkyl includehydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl and2-hydroxy-2-methylpropyl.

Unless otherwise stated or indicated, the term “cyano-C₁₋₆-alkyl”denotes a straight or branched C₁₋₆-alkyl group that has a hydrogen atomthereof replaced with cyano. Examples of said cyano-C₁₋₆-alkyl includecyanomethyl, 2-cyanoethyl, 2-cyanopropyl and 2-cyano-2-methylpropyl.

The derived expression “C₁₋₆-alkoxy” is to be construed accordinglywhere a C₁₋₆-alkyl group is attached to the remainder of the moleculethrough an oxygen atom. For parts of the range “C₁₋₆-alkoxy” allsubgroups thereof are contemplated such as C₁₋₅-alkoxy, C₁₋₄-alkoxy,C₁₋₃-alkoxy, C₁₋₂-alkoxy, C₂₋₆-alkoxy, C₂₋₅-alkoxy, C₂₋₄-alkoxy,C₂₋₃-alkoxy, C₃₋₆-alkoxy, C₄₋₅-alkoxy, etc. Examples of said“C₁₋₆-alkoxy” include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,isobutoxy, sec-butoxy, t-butoxy and straight- and branched-chain pentoxyand hexoxy etc.

Unless otherwise stated or indicated, the term “C₁₋₆-alkoxy-C₁₋₆-alkyl”refers to a C₁₋₆-alkoxy group that is bonded to a C₁₋₆-alkyl group viaan oxygen atom of said C₁₋₆-alkoxy group. Representative examples ofsuch groups include methoxymethyl and ethoxyethyl. Unless otherwisestated or indicated, the term “C₁₋₆-acyl” denotes a carbonyl group thatis attached through its carbon atom to a hydrogen atom (i.e., a formylgroup) or to a straight or branched C₁₋₅-alkyl group, where alkyl isdefined as above. For parts of the range “C₁₋₆-acyl” all subgroupsthereof are contemplated such as C₁₋₅-acyl, C₁₋₄-acyl, C₁₋₃-acyl,C₁₋₂-acyl, C₂₋₆-acyl, C₂₋₅-acyl, C₂₋₄-acyl, C₂₋₃-acyl, C₃₋₆-acyl,C₄₋₅-acyl, etc. Exemplary acyl groups include formyl, acetyl, propanoyl,butanoyl, pentanoyl, hexanoyl.

Unless otherwise stated or indicated, the term “C₁₋₆-alkylsulfonyl”refers to a straight or branched C₁₋₆-alkyl group that is bonded to asulfonyl group. Examples of C₁₋₆-alkyl-sulfonyl groups includemethylsulfonyl and ethylsulfonyl.

Unless otherwise stated or indicated, the term “heterocyclyl” or“heterocyclic ring” refers to a fully saturated or partiallyunsaturated, preferably fully saturated, monocyclic ring system having 4to 7 ring atoms with at least one heteroatom such as O, N, or S, and theremaining ring atoms are carbon. Examples of heterocyclic rings includepiperidinyl, tetrahydropyranyl, tetrahydrofuranyl, tetrahydrothienyl,azepinyl, azetidinyl, oxetanyl, thietanyl, pyrrolidinyl, morpholinyl,imidazolinyl, imidazolidinyl, thiomorpholinyl, pyranyl, dioxanyl,piperazinyl, homopiperazinyl and 5,6-dihydro-4H-1,3-oxazin-2-yl. Whenpresent, the sulfur atom may be in an oxidized form (i.e., S═O orO═S═O). Exemplary heterocyclic groups containing sulfur in oxidized formare 1,1-dioxido-thiomorpholinyl and 1,1-dioxido-isothiazolidinyl.

“Halogen” refers to fluorine, chlorine, bromine or iodine.

“Hydroxy” refers to the OH radical.

“Cyano” refers to the CN radical.

“Optional” or “optionally” means that the subsequently described eventor circumstance may but need not occur, and that the descriptionincludes instances where the event or circumstance occurs and instancesin which it does not.

“Pharmaceutically acceptable” means being useful in preparing apharmaceutical composition that is generally safe, non-toxic and neitherbiologically nor otherwise undesirable and includes being useful forveterinary use as well as human pharmaceutical use.

“Treatment” as used herein includes prophylaxis of the named disorder orcondition, or amelioration or elimination of the disorder once it hasbeen established.

“An effective amount” refers to an amount of a compound that confers atherapeutic effect on the treated subject. The therapeutic effect may beobjective (i.e., measurable by some test or marker) or subjective (i.e.,subject gives an indication of or feels an effect).

“Prodrugs” refers to compounds that may be converted under physiologicalconditions or by solvolysis to a biologically active compound of theinvention. A prodrug may be inactive when administered to a subject inneed thereof, but is converted in vivo to an active compound of theinvention. Prodrugs are typically rapidly transformed in vivo to yieldthe parent compound of the invention, e.g. by hydrolysis in the blood.The prodrug compound usually offers advantages of solubility, tissuecompatibility or delayed release in a mammalian organism (see Silverman,R. B., The Organic Chemistry of Drug Design and Drug Action, 2^(nd) Ed.,Elsevier Academic Press (2004), pp. 498-549). Prodrugs of a compound ofthe invention may be prepared by modifying functional groups, such as ahydroxy, amino or mercapto groups, present in a compound of theinvention in such a way that the modifications are cleaved, either inroutine manipulation or in vivo, to the parent compound of theinvention. Examples of prodrugs include, but are not limited to,acetate, formate and succinate derivatives of hydroxy functional groupsor phenyl carbamate derivatives of amino functional groups.

Throughout the specification and the appended claims, a given chemicalformula or name shall also encompass all salts, hydrates, solvates,N-oxides and prodrug forms thereof. Further, a given chemical formula orname shall encompass all tautomeric and stereoisomeric forms thereof.Stereoisomers include enantiomers and diastereomers. Enantiomers can bepresent in their pure forms, or as racemic (equal) or unequal mixturesof two enantiomers. Diastereomers can be present in their pure forms, oras mixtures of diastereomers. Diastereomers also include geometricalisomers, which can be present in their pure cis or trans forms or asmixtures of those.

The compounds of formula (I) may be used as such or, where appropriate,as pharmacologically acceptable salts (acid or base addition salts)thereof. The pharmacologically acceptable addition salts mentioned beloware meant to comprise the therapeutically active non-toxic acid and baseaddition salt forms that the compounds are able to form. Compounds thathave basic properties can be converted to their pharmaceuticallyacceptable acid addition salts by treating the base form with anappropriate acid. Exemplary acids include inorganic acids, such ashydrogen chloride, hydrogen bromide, hydrogen iodide, sulphuric acid,phosphoric acid; and organic acids such as formic acid, acetic acid,propanoic acid, hydroxyacetic acid, lactic acid, pyruvic acid, glycolicacid, maleic acid, malonic acid, oxalic acid, benzenesulphonic acid,toluenesulphonic acid, methanesulphonic acid, trifluoroacetic acid,fumaric acid, succinic acid, malic acid, tartaric acid, citric acid,salicylic acid, p-aminosalicylic acid, pamoic acid, benzoic acid,ascorbic acid and the like. Exemplary base addition salt forms are thesodium, potassium, calcium salts, and salts with pharmaceuticallyacceptable amines such as, for example, ammonia, alkylamines,benzathine, and amino acids, such as, e.g. arginine and lysine. The termaddition salt as used herein also comprises solvates which the compoundsand salts thereof are able to form, such as, for example, hydrates,alcoholates and the like.

Compositions

For clinical use, the compounds of the invention are formulated intopharmaceutical formulations for various modes of administration. It willbe appreciated that compounds of the invention may be administeredtogether with a physiologically acceptable carrier, excipient, ordiluent. The pharmaceutical compositions of the invention may beadministered by any suitable route, preferably by oral, rectal, nasal,topical (including buccal and sublingual), sublingual, transdermal,intrathecal, transmucosal or parenteral (including subcutaneous,intramuscular, intravenous and intradermal) administration.

Other formulations may conveniently be presented in unit dosage form,e.g., tablets and sustained release capsules, and in liposomes, and maybe prepared by any methods well known in the art of pharmacy.Pharmaceutical formulations are usually prepared by mixing the activesubstance, or a pharmaceutically acceptable salt thereof, withconventional pharmaceutically acceptable carriers, diluents orexcipients. Examples of excipients are water, gelatin, gum arabicum,lactose, microcrystalline cellulose, starch, sodium starch glycolate,calcium hydrogen phosphate, magnesium stearate, talcum, colloidalsilicon dioxide, and the like. Such formulations may also contain otherpharmacologically active agents, and conventional additives, such asstabilizers, wetting agents, emulsifiers, flavouring agents, buffers,and the like. Usually, the amount of active compounds is between 0.1-95%by weight of the preparation, preferably between 0.2-20% by weight inpreparations for parenteral use and more preferably between 1-50% byweight in preparations for oral administration.

The formulations can be further prepared by known methods such asgranulation, compression, microencapsulation, spray coating, etc. Theformulations may be prepared by conventional methods in the dosage formof tablets, capsules, granules, powders, syrups, suspensions,suppositories or injections. Liquid formulations may be prepared bydissolving or suspending the active substance in water or other suitablevehicles. Tablets and granules may be coated in a conventional manner.To maintain therapeutically effective plasma concentrations for extendedperiods of time, compounds of the invention may be incorporated intoslow release formulations.

The dose level and frequency of dosage of the specific compound willvary depending on a variety of factors including the potency of thespecific compound employed, the metabolic stability and length of actionof that compound, the patient's age, body weight, general health, sex,diet, mode and time of administration, rate of excretion, drugcombination, the severity of the condition to be treated, and thepatient undergoing therapy. The daily dosage may, for example, rangefrom about 0.001 mg to about 100 mg per kilo of body weight,administered singly or multiply in doses, e.g. from about 0.01 mg toabout 25 mg each. Normally, such a dosage is given orally but parenteraladministration may also be chosen.

Preparation of Compounds of the Invention

The compounds of formula (I) above may be prepared by, or in analogywith, conventional methods. The preparation of intermediates andcompounds according to the examples of the present invention may inparticular be illuminated by the following Scheme. Definitions ofvariables in the structures in schemes herein are commensurate withthose of corresponding positions in the formulae delineated herein.

whereinLG is a leaving group; andR¹, R² and a are as defined in formula (I).

Compounds of formula (I) may easily be synthesised by hydroxyalkylationof 4-chloropyridine with the appropriate benzaldehyde (II) to give anaryl-(4-chloro-pyridin-3-yl)-methanol derivative (III). Subsequentoxidation of the alcohol results in the correspondingaryl-(4-chloro-pyridin-3-yl)-methanone derivative (IV). Formation of thepyrazolo[4,3-c]pyridine ring system is accomplished by condensation of(IV) with hydrazine to give the 3-aryl-pyrazolo[4,3-c]pyridineintermediate (V). In the last step, the intermediate (V) is alkylated toinstall the appropriate heterocyclyl or heterocyclyl-alkyl group in thecompound of formula (I). A compound of formula (I) can optionally betransformed into another compound of formula (I).

The necessary starting materials for preparing the compounds of formula(I) are either commercially available, or may be prepared by methodsknown in the art.

The processes described below in the experimental section may be carriedout to give a compound of the invention in the form of a free base or asan acid addition salt. A pharmaceutically acceptable acid addition saltmay be obtained by dissolving the free base in a suitable organicsolvent and treating the solution with an acid, in accordance withconventional procedures for preparing acid addition salts from basecompounds. Examples of addition salt forming acids are mentioned above.

The compounds of formula (I) may possess one or more chiral carbonatoms, and they may therefore be obtained in the form of opticalisomers, e.g., as a pure enantiomer, or as a mixture of enantiomers(racemate) or as a mixture containing diastereomers. The separation ofmixtures of optical isomers to obtain pure enantiomers is well known inthe art and may, for example, be achieved by fractional crystallizationof salts with optically active (chiral) acids or by chromatographicseparation on chiral columns.

The chemicals used in the synthetic routes delineated herein mayinclude, for example, solvents, reagents, catalysts, and protectinggroup and deprotecting group reagents. Examples of protecting groups aret-butoxycarbonyl (Boc), benzyl and trityl (triphenylmethyl). The methodsdescribed above may also additionally include steps, either before orafter the steps described specifically herein, to add or remove suitableprotecting groups in order to ultimately allow synthesis of thecompounds. In addition, various synthetic steps may be performed in analternate sequence or order to give the desired compounds. Syntheticchemistry transformations and protecting group methodologies (protectionand deprotection) useful in synthesizing applicable compounds are knownin the art and include, for example, those described in R. Larock,Comprehensive Organic Transformations, VCH Publishers (1989); T. W.Greene and P. G. M. Wuts, Protective Groups in Organic Synthesis, 3^(rd)Ed., John Wiley and Sons (1999); L. Fieser and M. Fieser, Fieser andFieser's Reagents for Organic Synthesis, John Wiley and Sons (1994); andL. Paquette, ed., Encyclopedia of Reagents for Organic Synthesis, JohnWiley and Sons (1995) and subsequent editions thereof.

The following abbreviations have been used:

-   Ac Acetate-   Aq Aqueous-   Boc tert-Butoxycarbonyl-   Calcd Calculated-   Cbz Carboxybenzyloxy-   d Day-   DCM Dichloromethane-   DIAD Diisopropyl azodicarboxylate-   DIPEA Diisopropylethylamine-   DMF N,N′-Dimethylformamide-   ES⁺ Electrospray-   h Hour(s)-   HPLC High performance liquid chromatography-   HRMS High resolution mass spectrometry-   IR Infrared-   LCMS Liquid chromatography mass spectrometry-   M Molar-   [MH⁺] Protonated molecular ion-   min Minutes-   NMR Nuclear Magnetic resonance-   RP Reverse phase-   R_(T) Retention time-   MS Mass spectrometry-   sat Saturated-   sec Seconds-   THF Tetrahydrofuran-   TFA Trifluoroacetic acid-   TMS Tetramethylsilane

The recitation of a listing of chemical groups in any definition of avariable herein includes definitions of that variable as any singlegroup or combination of listed groups. The recitation of an embodimentherein includes that embodiment as any single embodiment or incombination with any other embodiments or portions thereof.

The invention will now be further illustrated by the followingnon-limiting examples. The specific examples below are to be construedas merely illustrative, and not limitative of the remainder of thedisclosure in any way whatsoever. Without further elaboration, it isbelieved that one skilled in the art can, based on the descriptionherein, utilize the present invention to its fullest extent. Allreferences and publications cited herein are hereby incorporated byreference in their entirety.

EXAMPLES AND INTERMEDIATE COMPOUNDS Experimental Methods

All reagents were commercial grade and were used as received withoutfurther purification, unless otherwise specified. Reagent grade solventswere used in all cases. Analytical LCMS was performed on a Waters ZQmass spectrometer connected to an Agilent 1100 HPLC system. AnalyticalHPLC was performed on an Agilent 1100 system. High-resolution massspectra (HRMS) were obtained on an Agilent MSD-TOF connected to anAgilent 1100 HPLC system. During the analyses the calibration waschecked by two masses and automatically corrected when needed. Spectraare acquired in positive electrospray mode. The acquired mass range wasm/z 100-1100. Profile detection of the mass peaks was used. Flashchromatography was performed on either a Flash Master Personal systemequipped with Strata SI-1 silica gigatubes or by gravity flashchromatography using Apollo Scientific silica gel (40-63 μm, 60 Å).Reverse Phase HPLC was performed on a Gilson system (Gilson 322 pumpwith Gilson 321 equilibration pump and Gilson 215 autosampler) equippedwith YMC ODS-A 100/150×20 mm columns. Preparative LCMS was performed ona Waters system (2× Gemini, X18, 110 Å, 50×21.2 mm, 5 nm). Microwaveirradiations were carried out using a Biotage microwave. The compoundswere automatically named using ACD 6.0.

Analytical HPLC and LCMS data were obtained with:

System A: Phenomenex Synergi Hydro RP (C18, 30×4.6 mm, 4 nm), gradient5-100% CH₃CN (+0.085% TFA) in water (+0.1% TFA), 1.5 mL/min, gradienttime 1.75 min, 200 nm, 30° C.; orSystem B: Phenomenex Synergi Hydro RP (C18, 150×4.6 mm, 4 nm), gradient5-100% CH₃CN (+0.085% TFA) in water (+0.1% TFA), 1.5 mL/min, gradienttime 7 min, 200 nm, 30° C.; orSystem C: Phenomenex Synergi Hydro RP-80A (C18, 150×4.6 mm, 4 nm),gradient 5-95% CH₃CN (+0.1% HCO₂H) in water (+0.1% HCO₂H), 1 mL/min,gradient time 15.5 min, 200-300 nm, 40° C.

Intermediate 1 3-(4-Chlorophenyl)-1H-pyrazolo[4,3-c]pyridine

Diisopropylamine (11.7 mL, 83.3 mmol) was dissolved in THF (200 mL)under a nitrogen atmosphere at 0° C. and n-butyllithium (52.5 mL, 1.6 Min hexanes, 84.0 mmol) was added. The solution was stirred for 1 h,cooled to −78° C. and 4-chloropyridine hydrochloride (5.00 g, 33.3 mmol)was added portionwise. The reaction mixture was stirred 2 h and4-chlorobenzaldehyde (4.68 g, 33.3 mmol) was added. The reaction mixturewas allowed to warm slowly to room temperature and stirred for 3 d. Sataq NH₄Cl solution (20 mL) was iii added and the reaction mixture waspoured into 1 M aq Na₂CO₃ solution (500 mL). The layers were separatedand the aq layer was extracted with DCM (2×500 mL). The combined organiclayers were dried (MgSO₄) and the solvents were removed in vacuo to give(4-chlorophenyl)-(4-chloro-pyridin-3-yl)-methanol (7.57 g, 89.4%) as alight brown solid.

Analytical HPLC: purity 77% (System B, R_(T)=4.55 min); Analytical LCMS:purity>90% (System A, R_(T)=1.66 min), ES⁺: 254.0 [³⁵ClMH]⁺ and 256.0[³⁷ClMH]⁺.

(4-Chlorophenyl)-(4-chloro-pyridin-3-yl)-methanol (7.57 g, 29.8 mmol)was dissolved in dry acetone (150 mL) and chromium (VI) oxide (8.94 g,89.4 mmol) was added. The reaction mixture was stirred for 18 h and thenpoured into sat aq NaHCO₃ solution (500 mL) and extracted with DCM(2×500 mL). The combined organic layers were dried (MgSO₄) and thesolvents were removed in vacuo. The residue was purified by columnchromatography (normal phase, 50 g, Strata SI-1, silica gigatube, DCM(600 mL)) to give (4-chlorophenyl)-(4-chloropyridin-3-yl)-methanone(4.88 g, 65.0%) as a yellow oil.

Analytical LCMS: purity 100% (System A, R_(T)=2.14 min), ES⁺: 252.0[³⁵ClMH]⁺ and 254.0 [³⁷ClMH]⁺.

(4-Chlorophenyl)-(4-chloropyridin-3-yl)-methanone (3.88 g, 15.4 mmol)was dissolved in MeOH (20 mL) at room temperature and hydrazine hydrate(20 mL) was added. The reaction mixture was stirred for 3 h. Theprecipitate was filtered and purified by recrystallisation fromPhMe/MeOH (˜4:1, ˜150 mL) to give3-(4-chlorophenyl)-1H-pyrazolo[4,3-c]pyridine (1.16 g, 33.0%) as ayellow solid.

Analytical HPLC: purity 99.2% (System B, R_(T)=4.29 min); AnalyticalLCMS: purity 94.8% (System B, R_(T)=4.69 min), ES⁺: 230.0 [³⁵ClMH]⁺ and232.1 [³⁷ClMH]⁺.

Intermediate 2 3-(4-Fluorophenyl)-1H-pyrazolo[4,3-c]pyridine

3-(4-Fluorophenyl)-1H-pyrazolo[4,3-c]pyridine was prepared according tothe method used for the preparation of Intermediate 1, but using4-fluorobenzaldehyde instead of 4-chlorobenzaldehyde. Excess MnO₂ wasused instead of CrO₃ in the oxidation step. The title compound wasobtained as a yellow solid (791 mg, 55.8% overall yield, 3 steps).

Analytical HPLC: purity 95.3% (System B, R_(T)=3.97 min); AnalyticalLCMS: purity>90% (System A, R_(T)=1.38 min), ES⁺: 214.4 [MH]⁺.

Intermediate 3 3-(4-Methylphenyl)-1H-pyrazolo[4,3-c]pyridine

3-(4-Methylphenyl)-1H-pyrazolo[4,3-c]pyridine was prepared according tothe method used for the preparation of Intermediate 1, but using4-methylbenzaldehyde instead of 4-chlorobenzaldehyde. Excess MnO₂ wasused instead of CrO₃ in the oxidation step. The title compound wasobtained as an off-white solid (2.05 g, 16% overall yield, 3 steps).Analytical LCMS: purity 100% (System C, R_(T)=3.26 min), ES⁺: 210 [MH]+.

Intermediate 4 4-(1H-Pyrazolo[4,3-c]pyridin-3-yl)-benzonitrile

4-(1H-Pyrazolo[4,3-c]pyridin-3-yl)-benzonitrile was prepared accordingto the method used for the preparation of Intermediate 1, but using4-formyl-benzonitrile instead of 4-chlorobenzaldehyde. The titlecompound was obtained as a white solid (846 mg, 28.8% overall yield, 3steps).

Analytical HPLC: purity 95.8% (System B, R_(T)=3.76 min); AnalyticalLCMS: purity>90% (System A, R_(T)=1.38 min), ES⁺: 221.4 [MH]⁺.

Example 13-(4-Fluorophenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine

Intermediate 2 (200 mg, 0.94 mmol) and triphenylphosphine (369 mg, 1.41mmol) were suspended in DCM (5 mL) and 4-hydroxytetrahydropyran (134 μL,1.41 mmol) was added, followed by DIAD (277 μL, 1.41 mmol). The reactionmixture was stirred for 3 d. The solvent was removed in vacuo to give ayellow gum. The residue was purified by reverse phase HPLC (YMC ODS-A100×20 mm, 5 μm, 25 mL/min, gradient 60% to 100% (over 7 min) then 100%(3 min) MeOH in 10% MeOH/water) to give3-(4-fluorophenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine(29 mg, 10.4%) as a white solid.

Analytical HPLC: purity 99.6% (System B, R_(T)=4.67 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.61 min), ES⁺: 298.5 [MH]⁺; HRMScalcd for C₁₇H₁₆FN₃O: 297.1277. found 297.1284.

Example 23-(4-Chlorophenyl)-2-(tetrahydro-2H-pyran-4-yl)-2H-pyrazolo[4,3-c]pyridine

Intermediate 1 (100 mg, 0.44 mmol) and triphenylphosphine (129 mg, 0.49mmol) were suspended in DCM (2 mL) and 4-hydroxytetrahydropyran (43.0μL, 0.45 mmol) and DIAD (97.0 μL, 0.49 mmol) were added. The reactionmixture was stirred for 5 d. The solvents were removed in vacuo and theresidue was purified by reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm,25 mL/min, gradient 40% to 100% (over 7 min) then 100% (3 min) MeOH in10% MeOH/water) to give3-(4-chlorophenyl)-2-(tetrahydro-2H-pyran-4-yl)-2H-pyrazolo[4,3-c]pyridine(11 mg, 7.8%) as a white solid.

Analytical HPLC: purity 99.5% (System B, R_(T)=4.97 min); AnalyticalLCMS: purity 100% (System B, R_(T)=5.34 min), ES⁺: 314.0 [³⁵ClMH]⁺ and316.0 [³⁷ClMH]⁺; HRMS calcd for C₁₇H₁₆ClN₃O: 313.0982. found 313.0980.

Example 33-(4-Methylphenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine

4-Hydroxytetrahydropyran (4.86 g, 47.6 mmol) was dissolved in DCM (40mL) and triethylamine (6.95 mL, 49.9 mmol). The reaction mixture wascooled to 0° C. and a solution of methanesulfonyl chloride (5.72 g, 49.9mmol) in DCM (10 mL) was added dropwise. The reaction mixture wasstirred at 0° C. for 5 min and then allowed to warm to room temperatureand stirred for 20 h. The solvents were removed in vacuo to give a whiteresidue which was partitioned between EtOAc and H₂O. The aq phase wasextracted with EtOAc (2×100 mL). The organic layers were combined, dried(MgSO₄) and the solvents were removed in vacuo to givetetrahydro-2H-pyran-4-yl methanesulfonate (8.53 g, 99%) as a colourlessgum which solidified on standing.

Intermediate 3 (0.40 g, 1.91 mmol), tetrahydro-2H-pyran-4-ylmethanesulfonate (1.03 g, 5.72 mmol) and K₂CO₃ (0.52 g, 3.76 mmol) weredissolved in MeCN (7 mL) and the reaction mixture was heated underreflux for 50 h. The solvents were removed in vacuo. The resultingresidue was partitioned between EtOAc (25 mL) and H₂O (25 mL). Theaqueous phase was extracted with EtOAc (2×100 mL). The organic layerswere combined, dried (MgSO₄) and the solvents were removed in vacuo. Theresidue was purified by Waters Preparative LC-MS (2× Gemini, X18, 110 Å,50×21.2 mm, 5 μm, 20 mL/min, 25° C., gradient 5% (held for 0.6 min) to100% (over 10 min), MeCN in H₂O (0.1% formic acid), 200-800 nm) to give3-(4-methylphenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine(103 mg, 18.6%) as an off-white solid.

Analytical HPLC: purity 99.0% (System B, R_(T)=9.02 min); AnalyticalLCMS: purity 100% (System B, R_(T)=8.39 min), ES⁺: 294.6 [MH]⁺; HRMScalcd for C₁₈H₁₉N₃O: 293.1528. found 293.1528.

Example 43-(4-Chlorophenyl)-1-[(3R)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine

Intermediate 1 (200 mg, 0.87 mmol) and triphenylphosphine (342 mg, 1.31mmol) were suspended in DCM (5 mL) and (S)-3-hydroxy-tetrahydrofuran(89.0 μL, 1.31 mmol) was added, followed by DIAD (257 μL, 1.31 mmol).The reaction mixture was stirred at room temperature for 48 h. Thesolvents were removed in vacuo. The residue was purified by reversephase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 60% to 100%(over 7 min) then 100% (3 min) MeOH in 10% MeOH/water) to give3-(4-chlorophenyl)-1-[(3R)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine(153 mg, 58.6%) as a light yellow gum.

Analytical HPLC: purity 100% (System B, R_(T)=4.78 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.88 min), ES⁺: 300.5 [³⁵ClMH]⁺ and302.5 [³⁷ClMH]⁺; HRMS calcd for C₁₆H₁₄ClN₃O: 299.0825. found 299.0831.

Example 5 3-(4-Chlorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine

Polymer-bound triphenylphosphine (1.81 g, 3 mmol/g, 5.44 mmol) wassuspended in DCM (10 mL) and stirred for 30 min. DIAD (1.07 mL, 5.44mmol), 1-Boc-4-hydroxypiperidine (1.09 g, 5.44 mmol) and Intermediate 1(500 mg, 2.18 mmol) were added. The reaction mixture was stirred at roomtemperature for 18 h. The reaction mixture was filtered and the filtrateconcentrated in vacuo. The residue was purified by reverse phase HPLC(YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 40% to 100% (over 7 min)then 100% (3 min) MeOH in 10% MeOH/water) to give4-[3-(4-chlorophenyl)-pyrazolo[4,3-c]pyridin-1-yl]-piperidine-1-carboxylicacid tert-butyl ester (200 mg, 22.2%) as a light yellow gum.

Analytical HPLC: purity 100% (System B, R_(T)=6.13 min); AnalyticalLCMS: purity>90% (System A, R_(T)=2.09 min), ES⁺: 412.9 [³⁵ClMH]⁺ and415.0 [³⁷ClMH]⁺.

4-[3-(4-Chlorophenyl)-pyrazolo[4,3-c]pyridin-1-yl]-piperidine-1-carboxylicacid tert-butyl ester (200 mg, 0.48 mmol) was dissolved in DCM (5 mL)and TFA (5 mL) was added. The reaction mixture was stirred at roomtemperature for 30 min. The solvents were removed in vacuo and theresidue was dissolved in 1 M aq Na₂CO₃ solution (50 mL) and extractedwith DCM (3×50 mL). The combined organic layers were dried (MgSO₄) andthe solvents removed in vacuo. The residue was purified by reverse phaseHPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 40% to 100% (over 7min) then 100% (3 min) MeOH in 10% MeOH/water) to give3-(4-chlorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]-pyridine (76 mg,50.2%) as a white solid.

Analytical HPLC: purity 100% (System B, R_(T)=3.74 min); AnalyticalLCMS: purity 100% (System B, R_(T)=3.60 min), ES⁺: 313.1 [³⁵ClMH]⁺ and315.0 [³⁷ClMH]⁺; HRMS calcd for C₁₇H₁₇ClN₄: 312.1142. found 312.1141.

Example 63-(4-Chlorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine

Polymer-bound triphenylphosphine (670 mg, 3 mmol/g, 2.00 mmol) wassuspended in DCM (5 mL) and stirred for 30 min. DIAD (396 μL, 2.01mmol), 4-hydroxy-N-methyl-piperidine (232 mg, 2.01 mmol) andIntermediate 1 (185 mg, 0.81 mmol) were added. The reaction mixture wasstirred for 18 h. The reaction mixture was filtered and the filtrateconcentrated in vacuo. The residue was purified by reverse phase HPLC(YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 60% to 100% (over 7 min)then 100% (3 min) MeOH in 10% MeOH/water), then by reverse phase HPLC(YMC ODS-A 150×20 mm, 5 μm, 15 mL/min, gradient 0% to 40% (over 12 min)then 100% (3 min) MeOH in water (1% formic acid)). The residue wasde-salted using K₂CO₃ in DCM to give3-(4-chlorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine(31 mg, 11.8%) as a white solid.

Analytical HPLC: purity 100% (System B, R_(T)=3.77 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.16 min), ES⁺: 327.0 [³⁵ClMH]⁺ and329.0 [³⁷ClMH]⁺; HRMS calcd for C₁₈H₁₉ClN₄: 326.1298. found 326.1303.

Example 7{4-[3-(4-Chlorophenyl)-1H-pyrazolo[4,3-c]pyridin-1-yl]piperidin-1-yl}acetonitrile

Example 5 (185 mg, 0.59 mmol) was dissolved in DMF (5 mL) and DIPEA(91.6 mg, 123 μL, 0.71 mmol) and iodoacetonitrile (51.0 μL, 0.71 mmol)were added. The reaction mixture was heated using a Biotage microwave(100° C., absorption high, pre-stirring 30 sec) for 10 min, and thenconcentrated in vacuo. The residue was dissolved in MeOH (5 mL), pouredinto 1 M aq Na₂CO₃ solution (50 mL) and extracted with EtOAc (3×50 mL).The combined organic layers were dried (MgSO₄) and concentrated invacuo. The residue was purified by reverse phase HPLC (YMC ODS-A 100×20mm, 5 μm, 25 mL/min, gradient 60% to 100% (over 7 min) then 100% (3 min)MeOH in 10% MeOH/water) to give{4-[3-(4-chlorophenyl)-1H-pyrazolo[4,3-c]pyridin-1-yl]piperidin-1-yl}acetonitrile(86 mg, 41.4%) as a cream solid.

Analytical HPLC: purity 97.9% (System B, R_(T)=4.57 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.61 min), ES⁺: 352.5 [³⁵ClMH]⁺ and354.5 [³⁷ClMH]⁺; HRMS calcd for C₁₉H₁₈ClN₅: 351.1251. found 351.1246

Example 83-(4-Chlorophenyl)-1-(tetrahydro-2H-pyran-4-ylmethyl)-1H-pyrazolo[4,3-c]pyridine

Sodium hydride (52 mg, 60% dispersion in mineral oil, 1.31 mmol) wassuspended in THF (3 mL) and Intermediate 1 (200 mg, 0.87 mmol) and4-bromomethyltetrahydropyran (187 mg, 1.04 mmol) were added. Thereaction mixture was heated using a Biotage microwave (100° C.,absorption normal, pre-stirring 15 sec) for 1 h, then at 120° C. for 1 hand at 125° C. for 30 min, and then concentrated in vacuo. The residuewas poured into 1 M aq Na₂CO₃ solution (50 mL) and extracted with DCM(3×50 mL). The combined organic layers were dried (MgSO₄) andconcentrated in vacuo. The residue was purified by reverse phase HPLC(YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 60% to 100% (over 7 min)then 100% (3 min) MeOH in 10% MeOH/water and YMC ODS-A 150×20 mm, 5 μm,15 mL/min, gradient 4% to 100% (over 12 min) then 100% (3 min) MeOH+1%formic acid in water+1% formic acid). The residue was de-salted usingK₂CO₃ in DCM to give3-(4-chlorophenyl)-1-(tetrahydro-2H-pyran-4-ylmethyl)-1H-pyrazolo[4,3-c]pyridineas a yellow gum (106 mg, 0.33 mmol, 37.1%).

Analytical HPLC: purity 100% (System B, R_(T)=4.99 min); AnalyticalLCMS: purity 100% (System B, R_(T)=5.38 min), ES⁺: 328.0 [³⁵ClMH]⁺ and330.0 [³⁷ClMH]⁺; HRMS calcd for C₁₈H₁₈ClN₃O: 327.1138. found 327.1149.

Example 93-(4-Chlorophenyl)-1-[1-(methylsulfonyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]pyridine

Example 5 (123 mg, 0.39 mmol) was dissolved in DCM (5 mL) and DIPEA (75μL, 0.43 mmol) and methanesulfonyl chloride (33.5 μL, 0.43 mmol) wereadded. The reaction mixture was stirred for 2 h, diluted with DCM (50mL), washed with 1 M aq Na₂CO₃ solution (50 mL) and the organic layerwas dried (MgSO₄) and concentrated in vacuo. The residue was purified byreverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 40%to 100% (over 7 min) then 100% (3 min) MeOH in 10% MeOH/water) to give3-(4-chlorophenyl)-1-[1-(methylsulfonyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]pyridine(61 mg, 39.7%) as a white solid.

Analytical HPLC: purity 100% (System B, R_(T)=4.98 min); AnalyticalLCMS: purity 100% (System B, R_(T)=5.03 min), ES⁺: 391.5 [³⁵ClMH]⁺ and393.6 [³⁷ClMH]⁺; HRMS calcd for C₁₈H₁₉ClN₄O₂S: 390.0917. found 390.0926.

Example 101-(1-Acetylpiperidin-4-yl)-3-(4-chlorophenyl)-1H-pyrazolo[4,3-c]pyridine

Example 5 (167 mg, 0.53 mmol) was dissolved in DCM (5 mL) and DIPEA (102μL, 0.59 mmol) and acetyl chloride (41.5 μL, 0.59 mmol) were added. Thereaction mixture was stirred for 2 h, diluted with DCM (50 mL), washedwith 1 M aq Na₂CO₃ solution (50 mL) and the organic layer was dried(MgSO₄) and concentrated in vacuo. The residue was purified by reversephase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 60% to 100%(over 7 min) then 100% (3 min) MeOH in 10% MeOH/water), dissolved inEtOAc (50 mL), washed with 1 M aqueous HCl (50 mL), dried (MgSO₄) andconcentrated in vacuo to give1-(1-acetylpiperidin-4-yl)-3-(4-chlorophenyl)-1H-pyrazolo[4,3-c]pyridine(35 mg, 18.6%) as a white solid.

Analytical HPLC: purity 100% (System B, R_(T)=4.62 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.70 min), ES⁺: 355.6 [³⁵ClMH]⁺ and357.5 [³⁷ClMH]⁺; HRMS calcd for C₁₉H₁₉ClN₄O: 354.1247. found 354.1263.

Example 113-(4-Chlorophenyl)-1-[1-(2-methoxyethyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]pyridine

Example 5 (162 mg, 0.52 mmol) was dissolved in DMF (5 mL) and DIPEA (108μL, 0.62 mmol) and (2-bromoethyl)methyl ether (58 μL, 0.62 mmol) wereadded. The reaction mixture was heated using a Biotage microwave (100°C., absorption high, pre-stirring 30 sec) for 10 min and at 120° C. for10 min, and then concentrated in vacuo. The residue was dissolved inMeOH (5 mL), poured into 1 M aq Na₂CO₃ solution (50 mL) and extractedwith EtOAc (3×50 mL). The combined organic layers were dried (MgSO₄) andconcentrated in vacuo. The residue was purified by reverse phase HPLC(YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 60% to 100% (over 7 min)then 100% (3 min) MeOH in 10% MeOH/water and YMC ODS-A 100×20 mm, 5 μm,25 mL/min, gradient 60% to 90% (over 7 min) then 100% (3 min) MeOH in10% MeOH/water) to give3-(4-chlorophenyl)-1-[1-(2-methoxyethyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]pyridine(29 mg, 15.0%) as a colourless gum.

Analytical HPLC: purity 99.8% (System B, R_(T)=3.96 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.01 min), ES⁺: 371.6 [³⁵ClMH]⁺ and373.5 [³⁷ClMH]⁺; HRMS calcd for C₂₀H₂₃ClN₄O: 370.1560. found 370.1575.

Example 123-(4-Chlorophenyl)-1-piperidin-3-yl-1H-pyrazolo[4,3-c]pyridine

Intermediate 1 (200 mg, 0.87 mmol) and triphenylphosphine (342 mg, 1.31mmol) were suspended in DCM (5 mL) and 1-Boc-3-hydroxypiperidine (263mg, 1.31 mmol) and DIAD (257 μL, 1.31 mmol) were added. The reactionmixture was stirred for 3 h and TFA (3 mL) was added. The reactionmixture was stirred for 1 h and concentrated in vacuo. The residue wasdissolved in 1 M aq HCl (50 mL) and washed with DCM (2×30 mL). The aqlayer was basified with NaOH and extracted with DCM (3×50 mL). Thecombined organic extracts were dried (MgSO₄) and concentrated in vacuo.The residue was purified by reverse phase HPLC (YMC ODS-A 100×20 mm, 5μm, 25 mL/min, gradient 60% to 100% (over 7 min) then 100% (3 min) MeOHin 10% MeOH/water) to give3-(4-chlorophenyl)-1-piperidin-3-yl-1H-pyrazolo[4,3-c]pyridine (41 mg,15.1%) as a white solid.

Analytical HPLC: purity 98.2% (System B, R_(T)=3.85 min); AnalyticalLCMS: purity 100% (System B, R_(T)=3.86 min), ES⁺: 313.6 [³⁵ClMH]⁺ and315.6 [³⁷ClMH]⁺; HRMS calcd for C₁₇H₁₇ClN₄: 312.1142. found 312.1152.

Example 133-(4-Chlorophenyl)-1-[(3S)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine

Intermediate 1 (200 mg, 0.87 mmol) and triphenylphosphine (342 mg, 1.31mmol) were suspended in DCM (5 mL) and (R)-3-hydroxy-tetrahydrofuran (89μL, 1.31 mmol) and DIAD (257 μL, 1.31 mmol) were added. The reactionmixture was stirred for 4 h and concentrated in vacuo. The residue waspurified by reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min,gradient 60% to 100% (over 7 min) then 100% (3 min) MeOH in 10%MeOH/water) to give3-(4-chlorophenyl)-1-[(3S)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine(160 mg, 61.3%) as a colourless gum.

Analytical HPLC: purity 100% (System B, R_(T)=4.82 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.86 min), ES⁺: 300.5 [³⁵ClMH]⁺ and302.5 [³⁷ClMH]⁺; HRMS calcd for C₁₆H₁₄ClN₃O: 299.0825. found 299.0835.

Example 143-(4-Chlorophenyl)-1-(tetrahydrofuran-3-ylmethyl)-1H-pyrazolo[4,3-c]pyridine

Intermediate 1 (200 mg, 0.87 mmol) and triphenylphosphine (342 mg, 1.31mmol) were suspended in DCM (5 mL) and tetrahydro-3-furan-methanol (126μL, 1.31 mmol) and DIAD (257 μL, 1.31 mmol) were added. The reactionmixture was stirred for 3 d and concentrated in vacuo. The residue waspurified by reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min,gradient 60% to 100% (over 7 min) then 100% (3 min) MeOH in 10%MeOH/water) to give3-(4-chlorophenyl)-1-(tetrahydrofuran-3-ylmethyl)-1H-pyrazolo[4,3-c]pyridine(118 mg, 43.2%) as a colourless gum.

Analytical HPLC: purity 99.7% (System B, R_(T)=4.88 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.94 min), ES⁺: 314.6 [³⁵ClMH]⁺ and316.5 [³⁷ClMH]⁺; HRMS calcd for C₁₇H₁₆ClN₃O: 313.0982. found 313.0990.

Example 153-(4-Chlorophenyl)-1-(1-ethylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine

Example 5 (162 mg, 0.52 mmol) was dissolved in DMF (5 mL) and DIPEA(99.0 μL, 0.57 mmol) and iodoethane (46 μL, 0.57 mmol) were added. Thereaction mixture was stirred for 11 d and concentrated in vacuo. Theresidue was dissolved in MeOH (5 mL), poured into 1 M aq Na₂CO₃ solution(50 mL) and extracted with DCM (2×50 mL). The combined organic layerswere dried (MgSO₄) and concentrated in vacuo. The residue was purifiedby reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient60% to 100% (over 7 min) then 100% (3 min) MeOH in 10% MeOH/water) togive3-(4-chlorophenyl)-1-(1-ethylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine(60 mg, 33.9%) as a colourless gum.

Analytical HPLC: purity 97.7% (System B, R_(T)=3.89 min); AnalyticalLCMS: purity 100% (System B, R_(T)=3.94 min), ES⁺: 341.5 [³⁵ClMH]⁺ and343.4 [³⁷ClMH]⁺; HRMS calcd for C₁₉H₂₁ClN₄: 340.1455. found 340.1465.

Example 163-(4-Chlorophenyl)-1-(1-isopropylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine

Example 5 (257 mg, 0.82 mmol) was dissolved in DCM (10 mL) and acetone(121 μL, 1.64 mmol), 4 Å molecular sieves (560 mg) and AcOH (1 drop)were added. The reaction mixture was stirred for 4 h and NaBH(OAc)₃ (184mg, 1.64 mmol) was added. The reaction mixture was stirred for 16 h.Acetone (200 μL) and NaBH(OAc)₃ (200 mg) were added and the reactionmixture was stirred for 4 d. 1 M aq Na₂CO₃ (2 mL) was added and thereaction mixture was stirred for 1 h, poured into 1 M aq Na₂CO₃ solution(50 mL) and extracted with DCM (3×50 mL). The combined organic layerswere dried (MgSO₄) and concentrated in vacuo. The residue was purifiedby reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient60% to 100% (over 7 min) then 100% (3 min) MeOH in 10% MeOH/water) togive3-(4-chlorophenyl)-1-(1-isopropylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine(102 mg, 35.0%) as a colourless gum.

Analytical HPLC: purity 97.2% (System B, R_(T)=3.98 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.05 min), ES⁺: 355.5 [³⁵ClMH]⁺ and357.5 [³⁷ClMH]⁺; HRMS calcd for C₂₀H₂₃ClN₄: 354.1611. found 354.1628.

Example 173-(4-Fluorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine

Intermediate 2 (200 mg, 0.94 mmol) and triphenylphosphine (369 mg, 1.41mmol) were suspended in DCM (5 mL) and 4-hydroxy-1-methylpiperidine (162mg, 1.41 mmol) and DIAD (277 μL, 1.41 mmol) were added. The reactionmixture was stirred for 3 d and concentrated in vacuo. The residue wassuspended in 1 M HCl (50 mL), washed with DCM (2×30 mL), basified withNaOH and extracted with DCM (3×50 mL). The combined organic extractswere dried (MgSO₄) and concentrated in vacuo. The residue was purifiedby reverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient60% to 100% (over 7 min) then 100% (3 min) MeOH in 10% MeOH/water) togive3-(4-fluorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridineas a pale yellow gum (35 mg, 12.0%).

Analytical HPLC: purity 99.5% (System B, R_(T)=3.50 min); AnalyticalLCMS: purity 100% (System B, R_(T)=3.51 min), ES⁺: 311.5 [MH]⁺; HRMScalcd for C₁₈H₁₉FN₄: 310.1594. found 310.1602.

Example 183-(4-Fluorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine

Intermediate 2 (200 mg, 0.94 mmol) and PPh₃ (369 mg, 1.41 mmol) weresuspended in DCM (5 mL). N-Boc-4-hydroxypiperidine (283 mg, 1.41 mmol)and DIAD (277 μL, 1.41 mmol) were added. The reaction mixture wasstirred for 3 d, TFA (2 mL) was added and the reaction mixture wasstirred for 3 h and concentrated in vacuo. The residue was suspended in1 M HCl (50 mL), washed with DCM (2×30 mL), basified with NaOH andextracted with DCM (3×50 mL). The combined organic extracts were dried(MgSO₄) and concentrated in vacuo. The residue was purified by reversephase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 40% to 80%(over 7 min) then 100% (3 min) MeOH in 10% MeOH/water and YMC ODS-A100×20 mm, 5 μm, 15 mL/min, gradient 0% to 40% (over 12 min) then 100%(3 min) MeOH+1% HCO₂H in 10% MeOH/water+1% HCO₂H). The purifiedfractions were concentrated in vacuo by half, poured into 1 M aq Na₂CO₃solution (50 mL) and extracted with DCM (3×50 mL). The combined organiclayers were dried (MgSO₄) and concentrated in vacuo to give3-(4-fluorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine as acolourless gum (67 mg, 24.1%).

Analytical HPLC: purity 99.1% (System B, R_(T)=3.44 min); AnalyticalLCMS: purity 100% (System B, R_(T)=3.48 min), ES⁺: 297.6 [MH]⁺; HRMScalcd for C₁₂H₁₇FN₄: 296.1437. found 296.1449.

Example 194-[1-(Tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrile

Intermediate 4 (275 mg, 1.25 mmol) and PPh₃ (490 mg, 1.87 mmol) weresuspended in DCM (5 mL) and 4-hydroxytetrahydropyran (178 μL, 1.87 mmol)and DIAD (368 μL, 1.87 mmol) were added. The reaction mixture wasstirred for 18 h and concentrated in vacuo. The residue was purified byreverse phase HPLC (YMC ODS-A 100×20 mm, 5 μm, 25 mL/min, gradient 40%to 80% (over 7 min) then 100% (3 min) MeOH in 10% MeOH/water) and bycolumn chromatography (normal phase, 20 g, Strata SI-1, silica gigatube,heptane/EtOAc (1:1) (300 mL) then EtOAc (500 mL)) to give4-[1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrileas a white solid (140 mg, 36.8%).

Analytical HPLC: purity 99.9% (System B, R_(T)=4.61 min); AnalyticalLCMS: purity 100% (System B, R_(T)=4.33 min), ES⁺: 305.5 [MH]⁺; HRMScalcd for C₁₈H₁₆N₄O: 304.1324. found 304.1334.

Example 204-[1-(1-Methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrile

Intermediate 4 (275 mg, 1.25 mmol) and PPh₃ (490 mg, 1.87 mmol) weresuspended in DCM (5 mL) and 4-hydroxy-1-methylpiperidine (216 mg, 1.87mmol) and DIAD (368 μL, 1.87 mmol) were added. The reaction mixture wasstirred for 18 h and concentrated in vacuo. The residue was dissolved inMeOH (5 mL), poured into 1 M aq Na₂CO₃ solution (50 mL) and extractedwith DCM (2×50 mL). The aq layer was basified with NaOH and extractedwith EtOAc (3×50 mL). The combined organic layers were dried (MgSO₄) andconcentrated in vacuo. The residue was purified by column chromatography(normal phase, 20 g, Strata SI-1, silica gigatube, DCM/EtOH/NH₃ 200:8:1(300 mL) then DCM/EtOH/NH₃ 100:8:1 (500 mL)) and by reverse phase HPLC(YMC ODS-A 100×20 mm, 5 μm, 15 mL/min, gradient 0% to 30% (over 12 mM)then 100% (3 min) MeOH+1% formic acid in 10% MeOH/water+1% formic acid).The residue was dissolved in 1 M aq Na₂CO₃ solution (25 mL), extractedwith DCM (2×25 mL), dried (MgSO₄) and concentrated in vacuo to give4-[1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrileas a white solid (46 mg, 12.6%).

Analytical HPLC: purity 99.5% (System B, R_(T)=3.34 min); AnalyticalLCMS: purity 100% (System B, R_(T)=3.31 min), ES⁺: 318.5 [MH]⁺; HRMScalcd for C₁₉H₁₉N₅: 317.1640. found 317.1649.

Biological Tests Biological Assay of the SSAO Enzyme Inhibitors

All assays were performed in room temperature with purifiedrecombinantly expressed human SSAO. Enzyme was prepared essentially asdescribed in Öhman et al. (Protein Expression and Purification 2006, 46,321-331). The enzyme activity was measured with benzylamine as substrateand utilized the production of hydrogen peroxide for detection. In ahorseradish peroxidise (HRP) coupled reaction, hydrogen peroxideoxidation of 10-acetyl-3,7-dihydroxyphenoxazine produced resorufin,which is a highly fluorescent compound (Zhout and Panchuk-Voloshina.Analytical Biochemistry 1997, 253, 169-174; Amplex® Red HydrogenPeroxide/peroxidise Assay kit, Invitrogen A22188).

Briefly, test compounds were dissolved in dimethyl sulfoxide (DMSO) to aconcentration of 10 mM. Dose-response measurements were assayed byeither creating 1:10 serial dilutions in DMSO to produce a 7 point curveor by making 1:3 serial dilutions in DMSO to produce 11 point curves.The top concentrations were adjusted depending on the potency of thecompounds and subsequent dilution in reaction buffer (50 mM sodiumphosphate, pH 7.4) yielded a final DMSO concentration≦2%. Enzyme andcompounds were set to pre-incubate in flat-bottomed microtiter platesfor approximately 60 minutes before initiating the reaction by additionof a mixture of HRP, benzylamine and Amplex reagent. Fluorescenceintensity was then measured at several time points (15 minutes, 20minutes and 30 minutes) exciting at 544 nm and reading the emission at590 nm). Final concentrations of the reagents in the assay wells were:SSAO enzyme 2 μg/ml, benzylamine 100 μM, Amplex reagent 20 μM, HRP 0.1U/mL and varying concentrations of test compound. The inhibition wasmeasured as % decrease of the signal compared to a control withoutinhibitor (only diluted DMSO). The background signal from a samplecontaining no SSAO enzyme was subtracted from all data points. Data wasfitted to a four parameter logistic model and IC₅₀ values werecalculated using the GraphPad Prism 4 or XLfit 4 programs.

The exemplified compounds of the invention generally had an IC₅₀ valueof 10 to 1000 nM. Obtained IC₅₀ values for representative compounds areshown in the table below:

Compound IC₅₀ (nM) Example 3 89 Example 5 120

1. A compound of formula (I),

or a pharmaceutically acceptable salt, geometrical isomer, tautomer,optical isomer or N-oxide thereof, wherein: R¹ is one, two or threesubstituents independently selected from halogen, cyano, C₁₋₆-alkyl,halo-C₁₋₆-alkyl and C₁₋₆-alkoxy; R² is a 4- to 7-membered saturated orpartially saturated heterocyclic ring containing 1 or 2 heteroatomsindependently selected from O, S and N(R³), and wherein ring carbonatoms are optionally substituted with R⁴; R³ is selected from hydrogen,C₁₋₆-alkyl, hydroxy-C₁₋₆-alkyl, cyano-C₁₋₆-alkyl, halo-C₁₋₆-alkyl,C₁₋₆-alkoxy-C₁₋₆-alkyl, C₁₋₆-acyl and C₁₋₆-alkylsulfonyl; R⁴ is selectedfrom halogen, hydroxy, C₁₋₆-alkyl, hydroxy-C₁₋₆-alkyl,C₁₋₆-alkoxy-C₁₋₆-alkyl, cyano-C₁₋₆-alkyl, halo-C₁₋₆-alkyl andC₁₋₆-alkoxy; and a is 0, 1 or 2; provided that the compound is not:3-(3,4-dichlorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine,or1-(1-methylpiperidin-4-yl)-3-[4-(trifluoromethyl)phenyl]-1H-pyrazolo[4,3-c]-pyridine.2. A compound according to claim 1 having formula (I′),

wherein R¹ is selected from halogen, cyano and C₁₋₄-alkyl; R² is a 5- to6-membered saturated or partially saturated heterocyclic ring containing1 or 2 heteroatoms independently selected from O, S and N(R³), andwherein ring carbon atoms are optionally substituted with R⁴; R³ isselected from hydrogen, C₁₋₄-alkyl, hydroxy-C₁₋₄-alkyl,cyano-C₁₋₄-alkyl, halo-C₁₋₄-alkyl, C₁₋₄-alkoxy-C₁₋₄-alkyl, C₁₋₄-acyl andC₁₋₄-alkylsulfonyl; R⁴, if present, is independently selected fromC₁₋₄-alkyl, halo-C₁₋₄-alkyl, hydroxy-C₁₄-alkyl andC₁₋₄-alkoxy-C₁₋₄-alkyl; and a is 0 or
 1. 3. A compound according toclaim 1 having formula (I″),

wherein R¹ is selected from halogen, cyano and C₁₋₄-alkyl; R² is asaturated 5- to 6-membered heterocyclic ring containing 1 heteroatomselected from O and N(R³), and wherein ring carbon atoms are optionallysubstituted with R⁴; R³ is hydrogen, C₁₋₄-alkyl or cyano-C₁₋₄-alkyl; andR⁴, if present, is independently methyl or ethyl.
 4. A compoundaccording to claim 1, which is selected from:3-(4-Fluorophenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-2-(tetrahydro-2H-pyran-4-yl)-2H-pyrazolo[4,3-c]pyridine;3-(4-Methylphenyl)-1-(tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-[(3R)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;{4-[3-(4-Chlorophenyl)-1H-pyrazolo[4,3-c]pyridin-1-yl]piperidin-1-yl}-acetonitrile;3-(4-Chlorophenyl)-1-(tetrahydro-2H-pyran-4-ylmethyl)-1H-pyrazolo[4,3-c]-pyridine;3-(4-Chlorophenyl)-1-[1-(methylsulfonyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]-pyridine;1-(1-Acetylpiperidin-4-yl)-3-(4-chlorophenyl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-[1-(2-methoxyethyl)piperidin-4-yl]-1H-pyrazolo[4,3-c]-pyridine;3-(4-Chlorophenyl)-1-piperidin-3-yl-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-[(3S)-tetrahydrofuran-3-yl]-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-(tetrahydrofuran-3-ylmethyl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-(1-ethylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Chlorophenyl)-1-(1-isopropylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Fluorophenyl)-1-(1-methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridine;3-(4-Fluorophenyl)-1-piperidin-4-yl-1H-pyrazolo[4,3-c]pyridine;4-[1-(Tetrahydro-2H-pyran-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrile;and4-[1-(1-Methylpiperidin-4-yl)-1H-pyrazolo[4,3-c]pyridin-3-yl]benzonitrile.5. A pharmaceutical formulation comprising a compound according to claim1 as an active ingredient, in combination with a pharmaceuticallyacceptable diluent or carrier.
 6. The pharmaceutical formulation ofclaim 5 wherein the active ingredient is present in an effective amountfor the treatment of inflammation, an inflammatory disease, an immune oran autoimmune disorder.
 7. The pharmaceutical formulation according toclaim 6, wherein the inflammation or inflammatory disease or immune orautoimmune disorder is arthritis, synovitis, vasculitis, a conditionassociated with inflammation of the bowel, atherosclerosis, multiplesclerosis, Alzheimer's disease, vascular dementia, a pulmonaryinflammatory disease, a fibrotic disease, an inflammatory disease of theskin, systemic inflammatory response syndrome, sepsis, an inflammatoryand/or autoimmune condition of the liver, diabetes (type I or II) and/orthe complications thereof, chronic heart failure, congestive heartfailure, an ischemic disease or myocardial infarction and/or thecomplications thereof.
 8. The pharmaceutical formulation according toclaim 6, wherein the inflammatory disease is vasculitis.
 9. Thepharmaceutical formulation according to claim 6, wherein theinflammation or inflammatory disease or immune or autoimmune disorder isrheumatoid arthritis, juvenile rheumatoid arthritis, osteoarthritis,psoriatic arthritis, Crohn's disease, ulcerative colitis, inflammatorybowel disease, irritable bowel syndrome, asthma, chronic obstructivepulmonary disease, acute respiratory distress syndrome, idiopathicpulmonary fibrosis, cardiac fibrosis, systemic sclerosis, contactdermatitis, atopic dermatitis, psoriasis, autoimmune hepatitis, primarybiliary cirrhosis, alcoholic liver disease, sclerosing cholangitis,autoimmune cholangitis, stroke, or ischemia-reperfusion injury.